The development of microfluidic technology, which handles and analyzes micro-liter or nanoliter volume of solution, has enabled the transition of the laboratory-on-a-chip (LOC) or microfluidic technology from research labs to industry. In the fields of chemistry and biology, microfluidic systems are increasingly used in applications such as transmission of trace fluid, micro synthesis, sample separation, composition analysis and chemical reaction.
Most microfluidic chips disclosed so far are electrophoresis chips, wherein molecules in solutions are driven by electrophoresis and/or electro-osmosis to the reaction surface. Electrophoresis chips can handle trace solution, but the repeatability and controllability of such a process are poor. On the other hand, fluid handling with a syringe is simple, but a relatively large volume of solution and reagent is usually consumed for such a procedure and hence waste of solution occurs frequently. Therefore, many researchers are developing various technologies and devices to use micro or nano-liter volume of fluid, and are particularly studying on manipulating and pumping different types of fluid of minute volume either sequentially or simultaneously. Many kinds of micro-pumps and micro-valves have been developed to ensure the precision and controllability of such a microfluidic process.